An attack on an American fort on this day gave birth to the country's national anthem, The Star Spangled Banner.

Ironically, since the United States was at war with Britain at the time in what became known as the War of Independence, the tune was the work of a British composer, the little known John Stafford Smith.

In 1814, Baltimore was not only America's third largest city (population 45,000), but also a port from where repeated attacks had been made against British ships.

Determined to teach them a lesson, British warships planned to sail into Baltimore harbour and attack the city with cannons, pounding it into submission. First, though, they needed to neutralise a fortress named Fort McHenry which protected the harbour entrance.

At 6.30 on the morning of 13 September the attack began and during the next 24 hours about 2,000 shells and 800 rockets were fired at the fortress.

Above it flew a giant American flag measuring 42 feet by 30 feet.

Watching the action from a distance was American lawyer, author, and amateur poet Francis Scott Key. When he saw that the huge flag was still flying at dawn the next day, signifying an American victory, he was inspired to write the poem, Defence of Fort McHenry.

Later, the words were set to John Stafford Smith's music, and renamed The Star Spangled Banner. It became a popular patriotic song.

Long thought to have originated as a drinking song, it was adopted in 1776 as a club anthem of the Anacreontic Society, an amateur mens’ music club in London. Its original lyrics were written by the Society’s president as an ode to a Greek poet named Anacreon.

With the substitution of Key's lyrics, the work became very popular in America and a powerful expression of patriotism. In 1916 it was proclaimed by President Woodrow Wilson to be the national anthem of all the armed forces. Finally, in 1931, under an Act of Congress, it became America's national anthem.